Hope that helps. For more info on how mortgage rates are priced, please read this blog entry: http://www.trulia.com/blog/gvd/2010/08/understanding_interes
The above rate was published by the Federal Reserve System and, although it's not disclosed in the Federal Reserve release, I suspect that rate applies to owner-occupied properties.
For more interest rate information, visit: http://www.bybryson.com/frames/interest.htm
If a rate is quoted so must an APR and the remaining terms. As with any loan there are many variables besides your credit. If you are considering purchasing a rental speak with a trusted mortgage professional to know ahead of time what you can qualify for.
Best of luck.
Looking at one of my rate sheets there is a 1.75 add to the fee if you are at 75% loan to value are less and a 3.0 add to the fee if you are more than 75% loan to value up to 80%.
In terms of how this translates, add .375% -.5% to a owner occupied rate with 25% or more down and add .5% -.625% for 20% down. So for example 4.5 for owner occupied becomes 4.875% or 5.00% for investment properties.
You will also need to have plenty of equity in your current home to be considered. Lenders are wary of buy and bail scenarios where people buy a second home, move in and quit paying on their first home.
I hope this helps.